Abstract: A dosimeter for use in mammographs wherein a plate-like body of electrically non-conductive hard foamed material generates charge carriers in response to exposure to radiation. The body is provided with electrodes which are connected with an energy source. The output signal of the dosimeter is used to regulate the amounts of radiation to which an object is exposed. The entire dosimeter can be installed between the source of radiation and X-ray film or another carrier of images of objects because the dosimeter does not cast a shadow on the film when the object is exposed to radiation.

Abstract: An ionography imaging chamber wherein the front side face of the pressure vessel is immediately adjacent to the foremost portion of the interelectrode gap and the image-receiving part of a dielectric receptor sheet in the gap extends into immediate proximity of the front side face. The front part of the margin of the sheet is bent over the front edge portion of one of the electrodes, and the gasket which seals the interelectrode gap while the latter is filled with compressed high Z gas abuts against the folded-over front part of the sheet. The sheet is attached to a drawer which carries one of the electrodes and is insertable into a compartment of the main section of the pressure vessel. One or more auxiliary electrodes are installed in the foremost portion of the gap to prevent distortion of latent images in the region which is nearest to the front side face of the pressure vessel.